Graphics professionals have relied upon PitStop Professional for years as the most comprehensive and powerful tool available for editing and preflighting PDF documents.

Licensing: Freeware Editions may be used for personal and commercial use on as many PCs as desired.
License keys of the Commercial Editions (Non-Site-Licenses) may be installed and used on one computer. Multiple licenses must be purchased for multiple installations.
Site Licenses may be installed and used on one or more computers owned by the licensee and located on one property owned by this person, company or institution (e.g. campus or business premises).

Website: www.paessler.com